Bobbling the ball doesn't make him defenseless, he had his head turned and was looking at Browner when the hit happened.
Yup, perfect explanation of why it was a bogus call, Browner wanted no part of helmet to helmet contact, pulled his head back so it didn't happen and still got flagged. At some point you have to let football be football, now we all know Browner's reputation but he did not commit a penalty on that play IMO, hell I've seen Welker take worse shots than that many times without a flag ever being thrown.